1. Field of the Invention
The present invention relates to an alternating current (AC)/direct current (DC) adaptor and a self-adaptive voltage output method.
2. Description of the Related Art
Referring to FIG. 1, a first conventional alternating current (AC)/direct current (DC) adaptor is adapted to provide two voltage signals with distinct levels to a respective one of a notebook computer (19V) and a mobile phone (5V). The AC/DC adaptor includes a first output connector 12 to be coupled electrically to the notebook computer, a second output connector 14 to be coupled electrically to the mobile phone, an AC/DC converter 10, a first DC/DC converter 11, and a second DC/DC converter 13.
The AC/DC converter 10 is coupled electrically with an AC power source (AC) which provides an AC voltage signal (110V) for receiving the AC voltage signal therefrom and for performing AC/DC conversion upon the AC voltage signal to obtain a DC voltage signal.
The first DC/DC converter 11 is coupled electrically to the AC/DC converter 10 for receiving the DC voltage signal therefrom, is coupled electrically to the first output connector 12, and adjusts a level of the DC voltage signal according to a fixed voltage buck rate so as to obtain a fixed first output voltage signal (19V). The first output voltage signal is provided to the notebook computer via the first output connector 12.
The second DC/DC converter 13 is coupled electrically to the first output connector 12 for receiving the first output voltage signal, is coupled electrically to the second output connector 14, and adjusts a level of the first output voltage signal according to a fixed voltage buck rate so as to obtain a fixed second output voltage signal (5V). The second output voltage signal is provided to the mobile phone via the second output connector 14.
However, the first conventional AC/DC adaptor has the following disadvantages:
1. Two of the first and second DC/DC converters 11 and 13, and two of the first and second output connectors 12 and 14 are required such that the cost is high.
2. The first and second output voltage signals are fixed in value such that there is some inconvenience during use.
Referring to FIG. 2, a second conventional AC/DC adaptor differs from the first conventional AC/DC adaptor in that the second AC/DC adaptor includes only one AC/DC converter 10, one DC/DC converter 11, and one output connector 12, and is adapted to convert an AC voltage signal (110V) into an output voltage signal (19V) to be provided to a notebook computer. When it is intended to provide electric power to an electronic device with a different requirement in voltage level, such as a mobile phone with the requirement of 5V, another DC/DC converter 13 is externally connected to the output connector 12 for converting the 19V output voltage signal into a 5V converted output voltage signal to be provided to the mobile phone. The second conventional AC/DC adaptor has similar disadvantages with respect to the first conventional AC/DC adaptor.